1. Technical Field
The present invention relates to a decorative article and a timepiece.
2. Related Art
An excellent appearance is required for decorative articles such as external parts of watches and other timepieces. Metals such as platinum and silver have traditionally been used to achieve this appearance.
The hardness of such metals, however, is generally low, decorative articles made from such materials are therefore easily scratched (particularly external timepiece parts and bracelets, for example), and the appearance of such articles deteriorates significantly with extended use.
To solve this problem, technologies such as nitriding, a process of adding nitrogen to the surface of stainless steel or titanium, for example, are used to increase the hardness of the base metal. See, for example, JP-A-H11-318520.
The nitriding process results in roughening the surface, however, and changes the polished appearance. This roughening is particularly noticeable on mirror-finished articles, which become cloudy, rendering such articles unusable as decorative parts.
One effect of the nitriding process is to make decorative articles that have been nitrided more resistant to scratching by relatively weak external forces. However, nitriding does not protect such decorative articles against relatively strong external forces, which can easily produce relatively deep scratches or indentations (such as scratches from being dropped). A problem with decorative articles that have been nitrided is that such indentations are made even more conspicuous as a result of being protected from small scratches.